Telephone-exchange system.



Patented Aug, 11, 1914.

3SHEETSSHEET 1.

E. B. CLEMENT.

TELEPHONE EXCHANGE SYSTEM APPLIGATION FILED JUNEZZ, 1906.

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TELEPHONE EXCHANGE SYSTEM APPLIUATIOB FILED JUNE 22, 1906 3SEEETS SHEET2.

CLEMENT. TELEPHONE EXCHANGE SYSTEM:

APPLICATION FILED JUNE 22, 1906.

UTE stares Par EDWARD E. CLEMENT, O VIASHINGTON, DISTRICT OF CGLUMBIA,ASSIGNS'R, BY

MESNE ASSIGNMENTS. TO FREDERICK C. STEVENS, OF ATTECA, NEW YORKTELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented filing. it,

To (ZZZ whom it may concern:

Be it known that I, EDWARD E. CLEMENT, a citizen of the United States,residing at ll ashington, in the District of Columbia, have inventedcertainnew and useful linprovements in Telephone-Exchange Systems, ofwhich the following is a specification, reference being had therein tothe accompanying drawing.

My invention relates to telephone exchange systems and has for itsprincipal ol ject the improvement of such systems by decreasing thenumber of operators required for a given number of lines andfacilitating their W01; to the highest possible degree.

In order to attain my object I employ a combination oi apparatus andcircuits, portions of which are of the well known manual type and otherportions automatic in their operation, such combinations being known assemi-automatic A very important corollary or subsidiary object of theinvention is to increase the capacity of existing exchange switch-boardsof the manual type and to render it possible to convert them intosemi-automatic equipments, at the same time increasing their efficiencyas well as their capacity.

Other objects will appear from tln description hereinafter.

Briefly stated, my invention comprises a system in which the subscriberslines terminate on the usual answering jacks in a manual switchboard,but instead of being provided with multiple acks for connectingpurposes, the lines are provided with multiple terminals in automaticswitchesot any desired or suitable type. The operator is provided withcord circuits of a single-plug type and terminating before the operatorin an answering plug. The usual supervisory lamp and relay for this plugare provided as well as a controlling relay, a cutoff and line relay foreach line, and an operators listening key. From the answering plug ofeach cord :1 pair of trunk conductors extend directly to an automaticselector switch containing multiple terminals through which thesubscribers lines may be called. Associated with the cord is a group ofkeys by which the operator may direct groups of impulses over the trunkto control the move ments of the automatic switch or switches, andfinally, automaticapparatus associated with the switching device teststhe wanted lines and sends out ringing current in case the line is foundclear.

This system is applied to existing manual plants by severing theordinary cord circuits and using them as I have described, each end ofthe ordinary cord circuit furnishing one complete terminal for anautomatic trunk. The subscribers lines are then disconnected from themultiple jacks, preferably at the intermediate distributing frame, sothat the multiple jack strips and their cable may be removed bodily.Experience demonstrates that an operator when relieved, as in this case,of the burdens of testing, ringing and supervising, can do more thantwice the work and can handle more than twice as many lines as under theold system. Thus, each operator can handle two positions, so that onlyhalf the number of operators are needed to manage the same switchboard,but where the capacity of the board is to be increased. answering jacksand lamps are added in the panels eft vacant by the removal of themultiple jacks. The number of automatic switches required, and theanmunt of cable and subsidiary apparatus, relatively small in cost whenthe increased capacity and the great eiliciency of the service are takeninto account.

hi invention is illustrated as to one embodiment in the accompanyingdrawings in which- Figure 1 is a diagram of a subscribers line and acentral oilice switchboard circuit in which it terminates, together withan answering plug and a portion of the cord circuit thereof. Fig. :2 isa similar diagram complemental to 1 showing a trunk ex tending from thecord circuit to an automatic switch. Fig. 3 is a diagram of theoperators controlling circuits and keys.

The system of my invention is herein illustrated and described asapplied to an exch ngc of but one hundred lines, but it is to beunderstood that the number of lines is limited only by the selectingapparatus oi:

Figs. 2 and 3, the selective apparatus of- Fig. 2 being of any desiredtype. 'Many types of impulse-controlled selective and connectiveapparatus are now known to the art, some of them providing forindefinitely large exchanges by a system of successive selectivedevices, the subscribers lines being found only in the last connector ofthe series of switches; lVith devices of Fig. 2 adapted to respond toimpulse control, in a manner well known to the art, the devices of Fig.3 require a similar extension in that the .sets of keys must beincreased to provide for the sending of as many sets of impulses as thedevices of Fig. 2 require, but the extension of the apparatus of Fig.3'is simply the'duplication of the sets of keys already shown in thatfigure.

Referring first to Fig. 1, A is a subscribers station equipped with theusual talking and signaling apparatus such as may be found in everymodern common battery exchange-system. This comprises a trans mitter,receiver, switch-hook, ringer and condenser, with or without aninduction coil according .to the make of the instruments used: In thediagram no induction C011 is shown, however. The line wires are marked1.-2-and extend to the central office C where they terminate upon thecontacts of the cutoff-relay N. These contacts are shown as armatures,but commercially they are usually contact springs controlled by the 3armature of the relay. They are normally electrically as shown,connecting the wire 1 to ground on one side, and wire '2 to line relay Mand thence by Wire 5 to the battery Ben the other. When the subscriberremoves his telephone from the hook, current will flow through the linerelay, energizing it and lighting the lamp on by closing the branchcircuit 6 to ground, Passing from front contacts of the cut-off relayare two extension wires 7 and '8 terminating at the answering jack- J Iand having parallel connections 9 and 10 to the multiples or connectingterminals 8 which are in the banks of several automatic switches,presently to be described.

Cooperating with the answering jack J is an answering plug P having tipand sleeve contacts through which the cord conductors 11 and 12 pass asfar as the condensers c, and 1 being inductively connected therethroughto the trunk conductors 13- and 14 leading to the automatic switch S ofFig. 2. Connected between the battery and the sleeveside 11 .fi-the cordcircuit is the relay R whichcontrols the battery supply to the armaturecontacts of, the supervisory relay Rflwhile passing through its owncoils is the supply of current both for the subscribers station intalking, and for the cut-off relay N which is usually made with 500ohmsresistan ce in its windings, composed of many turns of fine wireconnected in a ground tap through the sleeve Wire 7 of the lineextension. The supervisory relay R on the other hand is tapped off toground from the tip side 12 of the 0 1rd circuit, and"ClIIQCtIYICOIIlZIOlS the supervisory lamp '1' associated with'the plugP.

The trunk iretap-14 extend to a selector or connector switch orswitches, 6f which that shown in Fig. 2.is given as an example. As totheir mechanical parts, the switches are of the type shown in patents toKeith and Erickson, 815,176 and 815,321, both dated March 18, 1906; withthe exception that I prefer not to employ a so-called side switch shownin those patents, using purposes of control. The main mechanicalfeatures, however, are the same, hence 1 have not thought it necessaryto describe this type of switch herein except diagram matically. Thebanks of contacts 8, are in curved rows, each switch containing one ormoreof these rows as shown in the said patents, and having a spindle scarrying wipers s which are adapted to be broughtinte connection withany pair-of contacts in any row by a double motion of the spindle,- onecomponent of the motion being vertical produced by a ratchet controlledby the magnet 8 and the other component being rotary produced through acircular ratchet by the so-called rotary magnet 8 The trunk 1314 shownin the diagram, leads to the connector switch S, shown in Fig. 2, andthis switch is operated by means of impulses over the two sides of thetrunk, 9 in a manner which is generally familiar to those acquaintedwith the art. In order to do this I provide the operators with impulsetransmitters or senders. For eonvenience I will first describe thisarrangement as it is shown in Fig. 3, and will then proceed to point outits effect upon the apparatus of Fig. 2. In Fig. 3, Q Q, Q, Q Q Q, ,Q,etc., are a set .of wheels mounted on and turning with a common shaft,which may be driven in any suitable manner. The wheel Q", puts batteryand ground alternately on the Wire 29, which for purposes ofillustration represents the metallic shaft connection between thewheels. The wheel Q, which is insulated from the shaft is grounded, hasan insulating spot in its periphery, and controls by means of this spotthe locking and unlocking wires 30 and 31, in a manner which will appearfrom the statement of operation. The wheels QQ'QF, Q Q Q etc., arenumber wheels, tlre first one having one tooth, thesecond two teeth andso on up to ten teeth. (For simplicity of illustration only five wheelsare shown). Around these wheels are three sets of pens, connected to thethree sets of keys K, K K As the wheels revolve from the nor--- malposition of rest in which they are shown in the figure, they first makeconnection their buttons or keys, K, transmit the tens digit of anynumber, the next set transmit the units digit, and the third settransmit 130 with the upper pens, 9, then with the'pens then with those,9 The first set with th ringing number for party-line work. onlyfinishes setting up the number, but by All this will appear more clearlyfrom the closing the springs, 7:, puts ground on the statement ofoperation.

The keys, K, K are of the so-called self-latching selective ringin typenow in common use on manual switchboards, and employ the principle shownin the patent to 5 m, lIo. 605,097 granted June 7, 1898. l 'l hen anykey is pressed down it pushes buck the latch and releases the one thatwas previously dowinthen latching itself. The eye of each row arethus-interlocking, the ows being independent; thus one key of each rowremains depressed. Each set of has a common wire, this for the sets Kbeing marked 32, these two being ogether and carried to a hack conrelayPs while that for the set o the same relay, separately conpressing thekeys, and then the signal is started at is about to strike its pen bythe relay,

final locking position. The

remains energized. The trick of this is in the arrangement of the springpens 9, n the wheel C3. This wheel is rotated with the others in thedirection of the arrow, and its insulating spot passes first nder thespring pen g momentarily writing ground mi of that and the wire 31, thenunder the pen g taking ground off of that.

In calling to number wanted, which we will assume to be 32-3, theoperator plugs into the calling aclr, then presses down but-' ton No. 3of the set K; 2 of the set, K and l lo. 3 or" the K The buttons of thesets K ant K have their several individual wires connected to thesprings on the several individual wheels Q, Q3, etc, and the effect ofpressing down the buttons as mentioned is to connect the pen or" thethrough the springs of the butwire 82. A r the same time the pen g ofthe wheel Q} connected through the springs k of the button 1 6 to the wre 33 and the spring 9 of the wheel Q3 con-- nected through the springs70 of the button bite the wire 32. The also have what I may callstarting springs it". Keys of the type shown in Ham, cited, passdownward through a maximum travel and return slightly to engage thelocking shoulder. I take advantage of this and so adjust the springs 7cmax mum travel and return,

that they close at the break upon the slight being open when-the key isin its springs Z2,

- however, remain closed when the key is locked. or ringing set, thenumber is ready for transmission when any one of them is depressed,hence any one of these buttons not through up, and both lock, the

.Lhe numhersto be sent are set up.

the beginning of a rotation of the shaft, when the first tooth of eachwheel set of buttons, K"

call This set of buttons beingthe last,

starting wires 3'? and 38, which pass to the two relays, 3*, Rrespectively, and thence the common return wire 39 to battery B andground. Both the relays pull locking circuit of the relay B being asfollows: B, 39, R 7*, 30, 9, Q. and ground- The locking circuit of R isas follows: B, 39, R", 1' 31, g, Q and ground.

Having thus set up the signal in condition to be started at of arevolution of the main shaft, the operators work is finished. She paysno further attention to the connection until the subscribers havecompleted their conversation and have hung up, whereupon the relay t inFig. l lets go, and the lamp, 7', lights to call for disconnection. Theoperator then pulls the plug P.

The signal having been set up asdescribed, the apparatus of Fig. 3 thenoperates as follows: The wheel, Q, in revolving will bring theinsulating spot under the pen,

and put it the bcglnning 5 at first, and might thereby cut oil therelay, ll, prematurely, but this is provided for by making a branchlocking circuit 310 which controlled through a contact of the armature rand a. ground wire 36 of the starting relay Bi Hence, as long as therelay ll is energized, the relay ll cannot be affected. Moreover, itwill be observed that the wires 32 and 33 remain disconnected from'thowires 15l6 until the relay ll is energized, while the relay R isdeencrgizcd. This condition is br--1gl1t about when the insulating spotreaches the pen 9 he relay R then lets go, and we have a continuouscircuit from wire as follows: 32 34, 1' 16, and to trunk wire 1%. /Vealso have a circuit for wire 33 as follows: 33, T 35, r 15, and theother trunk wire Tho insulating spot reaches the pen 9* just before thefirst tooth on each wheel reaches its pen q; hence as soon as the abovedesired condition isattained, the set of battery impulses which has beendeter fined by the key is of the set K", comes over the wire 32 to thewire 16 and so onto the wire 1% of the trunk, through which it passesinto Fig. 2 to the relay R which will be presently described, and whichI shall for convenience the vertical relay. At the end of this group ofimpulses, the teeth on the wheels the pens g and so the next group ofground impulses determined by the key 70 will pass onto the wire 33 andso to the wire 15 and' the trunk wire 13, through which they reach therelay R in Fig. 2 which will also be presently described and which Ishall for convenience call the rotary relay. The names of these tworelays are quite accurate in this system,'because the relay B does willhave gotten around to really produce a vertical motion of the switch S,while the relay R produces a rotary motion thereof. At the end of thissecond group of impulses, the teeth on the wheels have gotten around tothe third set -of pens g and the battery impulses determined by the keysthen come through the wire 32 onto the wire 16 and so again to the trunkwire 14 and to the vertical relay R. After this, the insulating spot onthe wheel Q. reaches the spring 9 and momentarily cuts off the groundtherefrom. Since the relay R is already deenergized, this breaks thelocking circuit of the relay R and it'lets go, disconnecting the wires15- 16 from the wires 3534, and leaving the apparatus free for anotheroperation.

ieferring now to Fig. 2, I will briefly describe the switch operation.The switch spindle controls a pair of springs s which it opens when itis down in its normal position of disuse, for restoring purposes, aswill presently appear. 3 is the release magnet of the switch, which whenenergized removes the detent pawls from the respective ratchets of thespindle, .9, allowing the spindle to drop down and rotate back to zero,as fully described in the patents referred to. This release magnet isunder the control of the relay R which in turn is controlled by therelays R and R. It is also under the control of the test relay R. R is aringing-selection control relay, R is a trunk cut-off relay and R is aringing relay controlledby the connnutator X which is common to theentire exchange. R is a slow acting relay, preferably a solenoid, whichconnects the test relay R, as controlled by the first ringing impulse,and at the same time opens the generator circuit 40-4l, while the propercurrent is being selected. R to R, inclusive, are selective relays forenabling one or the other of the ringing generators, G, G, G and G ,tobe connected onto the ringing contacts of the ringing relay, R theparticular generator being determined by the number of impulses receivedthrough the relay R which operates the relays R R R R R R, insuccession, each of them looking as it operates. v

The operation of this trunk scheme is as follows: In selectingthe'number we have assumed 323: we have first three impulses over thewire 14 to the relay R, then twov ground impulses over the wire 13 tothe relay R", and then three impulses again over the wire 14 to therelay R. The first three impulses coming over the wire 14 caused therelay R to pull up three times, each time closing the following circuit:B, 42, 43, 44, s", 45, 46, 47, and ground to battery. The verticalmagnet 8 steps the spindle s of the switch up three steps, so that thewipers-.94 staald opposite the third row of contacts. Two impulsesthencome over wire 13, affecting the relay R which pulls up twice, thefirst time closing the following circuit: B, 42, 48,.R, 49, 50, armatureof R 51 to ground and to battery. The relay R instantly pulls up,cutting ofi? the vertical magnet, 8 and locking itself by the followingpath: B, 42, 48, R 9*", 52, 50, 51 and ground-back to battery. Thevertical magnet s is therefore cut ofi for the rest of the transmission.The rotary magnet 8, however,gets current each time the relay, R isenergized, over the following path: B, 42, 43, 44, s, 53, 54, 55 andground back'to battery. The rotary magnet 8* turns the spindle .9 twosteps, so that the wipers 8 rest on the second pair of contacts in thethird row, or No. 32. Three impulses now come over the wire 14, causingthe relay R again to pull up three times. Each time it closes thefollowing local circuit: B, 42, 56, R 57, 46,47, and ground back tobattery. As a branch of this same circuit, the wire 58 comes in frombattery wire 42 and goes to 57, 46, 47 and ground, so that the solenoidR is energized as well as the relay R At this point in the developmentof the connection immediately following the closure of the contacts ofrelay R at tliebeginning of thefirst generator-selection impulse, twothings occur simultaneously:

(1.) The solenoid R attracts its core, opening the wires 4041 andclosing the switch (32 whereby a test circuit is formed through elements13,42, 62, R 63, to upper 8', which at this moment is resting in contactwith the line selected through the agency of vertical and rotary magnetss 8*,- if the line be busy then a circuit will exist from upper wiper sto the'tip of the plug and through the relay R to ground in case theline tested has called or to another wiper s and thence through atrunking equipment following the'path through contact of R, contact of Rconductor 14 and winding of R to ground if that line has been called; ineither case the test relay R will be energized and in turn will energizethe release magnet 8. If, however, the selected line with which the testwiper rests in contact is not busy no cir-. cuit will exist from thattest wiper to ground and the test relay R wild not be energized; abranch, path from the con-' ductor 63 exists through the talkingconductor of the trunk to the left hand contact of relay R and thence toan armature contact of relay R where itterminates open, but subsequentto the energization of relay R as about to be described, this branchpath passes to the inn contact of the left hand armature of that relayand thence over the conductor 41 to the right hand switch of thesolenoid R which during the test period is open, and thus test .withrespect to those wheels relay R has its circuit open at all pointsanclrthe design of the device as a whole is that no. energization ofthat relay may result when the line selected is in a condition of disuseand subject to use in the connection now being established.

(2.) The relay 3 is energized over the path B, 42, 56, R 57, 46, 47 andground. By the closure of the left hand armature'of relay R circuit isformed through elements B, 42, 56, armature of R 60, Winding of B 61,switch 3 and ground, energizingrelay R which looks itself energized overthe circuit B, -12, armature and inner contact of relay R Winding ofrelay R 61, 8 and ground. This energization of trimk-connecting relay Rconnects the conductors 13, 14 of the trunk through to the outercontacts of the ringing relay R and through to the wipers s. Thisfurnishes a path through test relay 3 as follows :B, to, 24, 62, R 63,talkconductor to left-hand armature of R back contact and talkingconductor to armature of energized relay R conducto 14, winding of relayR and ground; however, this circuit is adapted to he opened by theattraction of the ii-matures of rela i, and it is the function of theconnector switch that the opening of this circuit at R shall succeed itsclosing at R by a time limit so small that restoration of the connectorswitch is not permitted. It will be noted in the study of this timeelement that the test relay it must attain the degree of mugnctizatirnrequired to attract its armatre, must swing its armature through itsfull travel to close its Contact, and that subsecucntly to the closureof the contact of the release magnc, must reach its re- 7 ed degree ofmagnetization and must overcome the inertia of its armature and more itthrough some definite are before release of the switch S will beeffected; this series of necessarily consecutive operations limits thedurstion of the momentary l aise test here considered. The commutuc )1X,

has been mentioned, is

'.' -d upon the shaft which carries the numbe, wheels and commutatordevices is)", Q. i the commutator X is ad}:

ducting portion of X all connection with its brush #1? the that theenergization of relay R cc It seen therefore that by the closing of thecontacts of relay R b which current iiow through test relay it waspermitted, current flow also was simultaneously provided for throughpath il, l), winding of R, contact and armature r, 5''? m and round.Thus current b through 1nd the w sumo through i suming equal speed inthe operation of illllllltlllQS, relay R will have moved its armatureand will have brokcudts back contact, thereby cutting otf curzeiit fromrelay R in ample time to prevent the rcstor; tion of the switch S byoperation of release magnet 8, the break at thearmature of It probablyoccurring in time to prevent any contact whatever at the armature ofrelay ll. Thus a test condition is maintained with the test wiper sisolated from the winding of relay R" by the break at the armature ofrelay it, and the design and adjustment of the con'unutator X shall besuch that the relay It is held energized throughout the maximum periodoccupied by gcnerator-selection impulses and until the opening of thecircuit of tlie test relay R by the opening of the switch (12 uponrelease of the armature of the solenoid R The armature of the solenoid Ris sluggish and does not open the switch 2 between thegeneratonselection impulses, so that the test circuit here described ismaintained continuously during the period of generator-selection.

Leaving the various parts of apparatus in the condition now considered,we will follow the action of the appa utus in response to the generatr-selection impulses. In the instance assumed, since station No. 3 is tobe called, three battery impulses will be received over the wire 1%operating the armature of the relay R successively three times, which inturn acts over the path 47, do, 57, it, etc. to operate the armatures ofrelay it in succession three times; the armature 1" through its frontand back contacts eli'ects the selection of the desired ringinggenerator as follows: Upon attraction of r by the firstg0nerator-selection impulse, it makes electrical connection with itsinner contact, but inasmuch the wire (H- is open at the armature ofrelay R no complete circuit is closed. Upon the release of the arnmturer at cessation of the lirstgenerator-selcctizm impulse, circuit isclosed through elcments'B, 2, 43, contact of R 60, 9', (15, contact of Rwinding of R and ground, energizing relay R which locks over the circuit13,42, 43, contact of R, (30, (if), Armature and contact of R winding ofii and ground. If but one generator-selection impulse were received, thegenerator G would remain in connection. with conductor 40 ready forconnection through conductor 41 to the ringing relay B. At the beginningof the second generator-selection impulse, relay R is energized andarmature it which then locks over the circuit 13,42, 43, contact of R60,69, armature contact and winding of R Upon the cessation of thesecond generator-selection impulse, the armature 1 is released, closingcircuit over B, 42, 43, contact of R 60, 1

'65, closed Contact of lower armature of energized relay It, backcontact of lower armature of unenergized relay R winding of relay R andground, energizing relay R which then locks itself through its owncontact by current received over conductor 69 to ground as in the caseof relays R and R. If no more generator-selection imulses were received,the effect of the' two impulses thus far followed would be to leavegenerator G connected to conductor 40 through contact of energized relayR, that being the proper generator for ringing the second station on aparty line. At the beginning of the third and last generatorselectionimpulse; the armature r is again attracted, closing circuit overelements 13, 42,43, contact of R 60, 1' 64, closed contact of energizedrelay R closed inner contact of energized relay R, closed outer confactof unenergized relay R winding of relay R" and ground, energizing relayR", which then locks itself by current through its own contact andWinding over conductor 69 to ground. Upon the cessation of the third andlast generatorselection impulse, the amature r is released, closingcircuit through elements B, 42, 43, contact of R 60, r, 65, closed innercontacts of energized relays R and R closed outer contact of unenergizedrelay R Winding of relay R and ground, energizing relay R which thenlocks itself by current through its own armature. contact and windingfrom conductor 69 to ground. This leaves relays R and R" energized andleaves relay R unenergized, thus effecting the connectionof generator Gto the conductor 40, and as the generator-selection impulses now cease,solenoid R releases its armature, opening the circuit of the test relayR and closingthe circuit between conductors 40-41, thus connecting theselected generator G over conductor 41 to the inner contact of the lefthand armature of ringing relay R and thus through the upper wiper s andto the lineconductor of the selected line to ring the third stationupon'the party line selected.

The ringing will continue until the insulatedportion of the'commutator Xpasses under the brush of that commutator when the circuit of thewinding of relay R Will be interrupted and by release of that relaysarmature the circuit from the wipers s will ergized and to periods ofnon-ringing when the relay R 'is de'energized. Upon theanswering of thecalled sub-station, or of any substation upon that party line, during aperiod of non-ringing, current immediately will flow through elements'B, 42, winding of R, 13, lower 5', line conductor, substation 70bridge, return line conductor, uppers 14, winding of R and earth,energizing R and attracting its. armatures.

By theoperation of the left hand armature of R, circuit isclosed throughele-' 7 ments B, 42, left hand armature and inner contact of R, windingof R 54, contact and left hand armature of-R, 55 and ground, energizingR which then locks over the circuit B, 42, right hand armature and thecondition of conversation and continues until the hanging up of thetelephone 9 and the breaking of the substation bridge upon the calledline; v

Upon the hanging up of the telephone and the breaking of the substationbridge upon the called line, disconnection of the 9 switch S is effectedas follows: Circuit is interrupted over the return wire of the line andthrough relay R to ground, releasing the armatnres of relay R, butcurrent continues through elements B, 42, Winding ofx R 13, lower wipers, and the sleeve side of the connected line and the winding of itscut-off relay N to ground, maintaining the energization of the relay R.By the release of the left hand armature of relay R a re- 1 lease relaycircuit is established through elements B, 42, left hand, armature andouter contact of deenergized relay R, winding of release relay R innercontact and armature 1 of relay R 51 and ground, energiz- 1 ing releaserelay R which, by closin its contact, energizes release magnets 3 wicheffects immediate restoration of all parts of the switch S to the normalposition of disuse. 1 A consideration of test conditions during theprocess of the connection is desirable. When the test wiper or upperwiper 8 connects with the test conductor of the line, no action is takeneither to test for busy or to place a busy test upon the line until thewheels Q, Q Q etc., have in due course of progress begun to send thegeneratorselection impulses; at this time, by the action of the solenoidR the selected line is tested for busy condition, the testing for busybeing continued throughout the receipt of the enerator-sele'ctionimpulses and the line bemg left unguarded against connection by otherconnectors; at the close of the V thereto. for an exchange of more thanill lines scribe generator-selection impulses, the test relay is takenoff and the ringing generator is substituted. Fronr this time a busytest guard condition is placed upon the test conductor of the selectedline, being alternately the potential of the selected ringing generatorwhen the relay .R is energized, which is sutficient to energize anyrelay R which may test the line during the interval of ringing, andbetween the intervals of ringing the busy test consists of the groundcir' cuit through the relay R. If the line thus connected with be testedfor busy by some other connector attempting a connection with it andduring the interval of deenergization of ringing relay R, a current willflow from the connector then testing to the test conductor of the line,thence through the test wiper of the connector of Fig/ 2.

holding the line, and through back contact of relay R, front contact ofR 28, and winding of R to ground. his current will be of suf icientstrength to energize the test relay R of. the distant connectorattempting to talte the line being held, and this will effectdisconnection of that connector but it will not be of sufficientstrength to energize the relay 1 1 inasmuch as by the energization andsubsequent deenergization of that relay, the said testing current wouldalso restore the holding connector of Fig. 2 to its normal condition ofidleness.

I have thus described and stated the operation of one form of myinvention. Many changes can be made therein without departing from thespirit thereof.

The equipment shown in the figures of the drawings herewith sullicicntas regards the automatic switching for an cxchange of lines or less, inwhich there are say ten of the switches shown in Fig. 7 each line havingten multiple contacts 8 Th invention is obviouslv applicable toexchanges of any size houercr, by merely extending the circuits andincreasing the operators in accordance with well understood rules. Theparticular form of switch employed is not material to the present invoution, nor are the switch circuits shown in Fig. 2 specificallynecessary. 'lhcy may he the same as those commonly mnploycd in lluStrowgor system, using the switches shown in.the Keith and Ericksonpatents hereinbefore referred to. The number of submay be anythingdesired, and the switchl apparatus shown in Fig. 2 will he sv.inetrically increased proportionally The trunk lines l4.l. 3 of Fig. 1.

would pass to a first selector swita, which would be. controlled in thesame manner as the swi ch illustrated in Fig. 2, by impulses over t ankwires, to pick out an auxiliary s which would then be controlled nextstep and so finally to selectthe line wanted. As this system ofswitching is familiar to those skilled in the. art, and i shown inLetters Patent, it is unnecessary for me to go further into it here. Theplugs P in front of an operator do, not represent any particular groupof subscribers but are merely terminals or" first selector or connectorswitches by which any subscriber in the exchange can be reached. Anexchange of 100 lines with connector switches only is shown, but as lhave stated, this might as well be 1,000 or IQQOGG. In case of numbershaving more than two digits, however, the number of sets of buttons inthe sending device of Fig. 3 would oi course have to be increasedaccordingly, one row of buttons and one additional set of contactsprings on the sending device being added for each digit. Thus, for a1,000 line exchange there would be four rows o buttons instead of three,in a 10,900 line exchange five rows and so on; one of the rows in eachcase being reserved for selective ringing as described herein.

My claims should be construed in view of the foregoing remarl-zs a theyare not intended to be limited to any particular numher or arrangementof automatic switches or any particular number of subscriber lines in anexchange. The gist of the invention lies in the combination andarrangementof the line terminals, the trunk plugs, the

switches for completing the connections and the operator's sendingcircuits.

ll aving thus described my invention, what I claim and desire to secureby Letters Pat cut is:

l. in a telephone system, the combination of subscribers lines, ananswering jack and a calling signal for each of said lines, auto. maticconnector switcl es in which i'nultiples of said lines appear, trunksfrom switching plugs to said automatic switches the plug ends of saidtrunks being adapted to connect with said answering jacks, and aconstantly-driven signal-sending device with locking signal-selectingkeys for controlling the movements of said automatic switch to connectits trunk to the terminals of a desired line.

2. la a telephone system the combination of subscribers" lines. acalling signal and answering jack for each of said lines, automaticconnector switches in which multiples of said lin'cs appear, trunks fromanswering plugs to said auton'iatic switches, and a constantly-driven s1rial-sending device with a desired line.

In a telephone system, the combination of subscribers lines, a ack andsignal tor each of said lines, automatic connector switches in whichmultiples of said lines appear, trunks to said automatic switches, aswitch plug for each trunk for connecting the trunk to a calling line,and a constantly driven signal-sending device with a bank of'lockingsignal-selecting keys per trunk for controlling the movements of saidautomatic switch throughout "a plurality of successive directory digitsto connect its trunk to the terminals of a desired line.

4. In a telephone system, the combination of subscribers lines, acalling jack and sig-. nal for each of said lines, automatlc connec- Vtor switches in which multiples of said lines appear, trunks to saidautomatic switches, manual means for connecting a calling line to one ofsaid automatic switches, and a constantly driven signal-sending devicewith a bank of locking signal-selecting keys, associated with each ofsaid trunks for controlling the movements of the automatic switch of thetrunk throughout a plurality of successive directory digits to connectthe trunk with a desired line.

5. In a telephone system, the combination of subscribers lines, a jackand signal for each of said lines, automatic connector switches in whichmultiples of said lines appear, trunks to said automatic switches, plugends on safil trunks to connect with said answering jacks, and aconstantly driven signal-sending device with looking selecting numberkeys for controlling the movements of said automatic switch to connectits trunk to the terminals of a desired line.

6'. In a telephone system, the combination of-subscribers lines, a jackand signal for each of said lines, automatic connector switches in whichmultiples of said lines appear, trunks to said automatic switches, plugends on said trunks to connect with said answering jacks, and aconstantly driven multiple-signal-sendin'g device with locking se--lecting number keys and associated with said trunks for controlling themovements of said automatic switches to connect the trunks to theterminals of desired lines.

7. In a telephone system, the combination of subscribers lines, a jackand signal for each of said lines, automatic connector switches in whichmultiples of said lines appear, trunks to said automatic switches'directly .from answering plugs, and a con stantly drivenmultiple-signal-sepding device for controlling the movcmeitsol anautomatic switch to connect its trunk to the terminals of a desiredline.

8. In a telephone system, the comliiimtion of subscribers lines, a jackand signal for each of 'said lines, automatic connector switches inwhichmultiples of said lines appear, trunks to said automatic switchesdirectly ircln answering plugs, and a constantly drivenmultiplesignal-scmling device for controlling the movements of anautomatic switch throughout a plurality of successive directory digitsto connect its trunk to the terminals of a desired line.

9. In a telephone system, the combination of subscribers lines, a jackand signal for each of said lines, automatic connector switches in whichmultiples of said lines.

appear, trunks to said automatic switches, single-plug manual switchingmeans for connecting a trunk and a calling line, aconstantly drivensignal-sending device, and locking signal-selecting keys associated with,,said trunks for controlling the movements of an automatic switch toconnect its trunk to a desired line.

10. In a telephone system, the eombination of subscribers lines, a ackand signal for each of said lines, automatic connector switches in whichmultiples of said lines appear, trunks to said automatic switches,manual switching means for connecting a 'calling line with a trunk toone of said automatic switches, a constantly driven signalsendingdevice, and locking signal-selecting keys associated with said trunksfor controlling the movements of an automatic switch' to connect itstrunk to the terminals of a desired line.

11. In a telephone system the combination of subscribers lines, a jackand signal for each of-fsaid lines, automatic connector.

switches in which multiples of saidlines-appear, trunks to saidautomatic switches, manual' means for connecting a calling line with atrunk to one of said automatic'switches, a constantly drivensignal-sending device, and locking signal-selecting keys associated witheach of said trunks for controlling the movements of its automaticswitch through a plurality of successive directory digits to connect'that trunk to the terminals of a desired line.

12. In a telephone system, the combination of subscribers lines, a jackand'signal for each of said lines, automatic connector switches in whichmultiples of said lines appear, trunks to said automatic switches, aconstantly-driven multiple-signal-sending device, manual means forconnecting a call-- ing line to a trunk to an automatic switch, and setsof lOClflll signal-selectlng keys for each of said trun s whereby 1tsautomatic switch may be controlled to-connect that trunk to theterminals of a desired line.

13. In a telephone system, the combination of subscribers lines, a jackand signal for each of said lines, automatic connector switches in whichmultiples of said lines appear, trunks to said aulomatic switches, aconstantly driven multiple-signal-scntling device, answering plugs forconnecting a trunk to a calling line, and sets of signal-selecting keysfor each of said trunks whereby the automatic switch of that trunk maybe conll'nllod throughout plurality oF successive directory digits toconnect that trunk to the terminals of a desired line.

1%. ln a telephone exchange system, a plurality of subscriber" lines, aplurality of automatic switches ard a trunk for each, isingleplugswitching means manually controll d by the operator for connecting anidle switch trunk to a calling line, automatic actuating means for theswitches adapted to be manually preset so as whole number of the linewanted, and unitary means for each trunk manually con trolled by theoperator for determining the application of said actuating means to saidtrunk, after setting up the number.

15. In a telephone exchange system, a plurality oi line circuits eachhaving a telephone and signal device at a substation, and a terminalanswering jack with an associated call signal at the central ofiice, anum ber of connective circuits each comprising an answering with saidjack, automatic switching apparatus for selecting and connecting with awanted line, and a trunk directly connected to and terminating in saidplug at one end and sin'iilarly connected to the switch at the other,and controlling means for said switchto transmit the plug adapted tocooperate.

ing apparatus adapted to be manually actuated by an operator, and inturn to actuate the switching apparatus, together with a common batterysource of energy supplying all of said elements including the talkingcircuit.

16. In a telephone exchange system, a subscribers line circuitterminating at a central otiice in an answering jack, an answering plugfor said jack, an automatic switching apparatus adapted to connect withvarious subscribers lines, a connective trunk directly connected at oneend to and terminating in said answering plug, and at the other endsimilarly connected to and terminating in said automatic switchingapparatus, and means manually controlled at the central ofiice foractuating said switching apparatus, together with supervisory signalapparatus for the connector switch at the plug end of said trunk.

In testimony whereof I afiix my signature in presence of two witnesses.

EDlVARD E. CLEMENT.

\Vitnesses:

E. Ennoxs'ron, Jr., Janus H. Mann.

